Customer registration just with e-mail address

[pinochico]

No, If I use OPC from Rupostel with this plugin, I can use for login existing username too == for login I can use username or email (This is exactly what plugin do it).

[gba]

It is not a bug. The reason is simple, it does not overwrite existing values. I need to add configuration options to decided if it should overwrite existing values, or not.
Imagine the other way round. A user changes just his email address and the login name changed "suddenly" and he cannot login. So both logics are valid. It depends on the use case.
Currently only the "email" is overwriting the old value, other values are checked against empty.

The authentication plugin of Richey is indeed interesting, cause it enables to use username and email.

Thank you very much!
(successfully tested in plugin version 1.2.2)